Cat collars are made with a different type of clasp than dog collars. Cat collars are made to separate with a little bit of pressure due to a cat’s tendency to squeeze through tight spaces. My cats are both indoor cats and remove their collars frequently. The older cat does it on purpose because he thinks his collar is a toy. The point being, cat collars can be very hard to keep attached. Absence doesn’t mean it doesn’t have a home.
I was making plans to get rid of a cat hammock because my cat never used it. Never wanted anything to do with the thing. As soon as I was ready to get rid of it, my cat started sleeping in it. They always know.